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Mosaicism in a new E ocene pufferfish highlights rapid morphological innovation near the origin of crown tetraodontiforms
Author(s) -
Close Roger A.,
Johanson Zerina,
Tyler James C.,
Harrington Richard C.,
Friedman Matt
Publication year - 2016
Publication title -
palaeontology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.69
H-Index - 63
eISSN - 1475-4983
pISSN - 0031-0239
DOI - 10.1111/pala.12245
Subject(s) - biology , evolutionary biology , clade , lineage (genetic) , skull , taxon , zoology , phylogenetic tree , body plan , paleontology , genetics , gene
Tetraodontiformes (pufferfishes and kin) is a taxonomically and structurally diverse, widely‐distributed clade of acanthomorphs, whose members often serve as models for genomics and, increasingly, macroevolutionary studies. Morphologically disparate P alaeogene fossils suggest considerable early experimentation, but these flattened specimens often preserve limited information. We present a three‐dimensionally preserved beaked tetraodontiform from the early E ocene ( c . 53 Ma) L ondon C lay F ormation, UK . Approximately coeval with the oldest crown tetraodontiforms, † C tenoplectus williamsi gen. et sp. nov. presents an unprecedented combination of characters, pairing a fused beak‐like dentition with prominent dorsal‐fin spines that insert atop transversely‐expanded pterygiophores roofing the skull. B ayesian total‐evidence tip‐dating analysis indicates that † C tenoplectus represents the sister lineage of T riodontidae and highlights considerable levels of homoplasy in early tetraodontiform evolution. According to our dataset, rates of morphological character evolution were elevated at the origin of crown T etraodontiformes, especially within gymnodonts, but declined after the principal body plans were established. Such ‘early burst’ patterns are regarded as a hallmark of adaptive radiations, but are typically associated with diversification at smaller spatiotemporal scales. However, denser sampling of N eogene and R ecent taxa is needed to confirm this pattern.